The idea that The Tempest takes place entirely in Prospero's mind is not a new one. But Tim Carroll's production pushes the premise to its theatrical limits with a three-actor version that puts Shakespeare's play on the Jungian couch.

Here, Ariel and Caliban represent spirit and soul: two opposing forces that pull Prospero one way and another, and are essentially part of him. Caliban is first seen emerging from under Prospero's magic cloak as if he embodied the darker side of the magician, deliberately kept hidden. The storm is represented by a battle on a chessboard that is overturned, the pieces scattered and lost; the scene of brotherly reconciliation sees the pieces restored.

These are neat little touches, but although the production is often interesting, it fails to be consistently arresting because the central conceit is seldom made a theatrical reality. This show remains an intellectual act, never a genuinely transforming, imaginative one. It burdens the play rather than illuminates it. Anyone unfamiliar with Shakespeare's play would have an impossible time working out the plot.

They might also be bemused by the presence of three women, in jeans and leather jackets, who strike poses. These dancers represent the unseen spirits of the enchanted island, and there are times, such as when the shipwrecked party are put into a magical sleep, when they are fully integrated into the action.

But one of the hallmarks of the production is its sheer messiness - whether it is the dancers, who are distracting and often hinder the storytelling, or the fatal lack of differentiation between characters (essential here, because the three actors play several roles each). Edward Hogg's Ariel and Miranda both look like ruffed choirboys and seem equally puzzled by the human world. And while Alex Hassell is excellent as Caliban, he makes harder work of Ferdinand and Gonzalo.

Most disappointing is Mark Rylance's Prospero, who only comes into his own in the final speech, when, hands in pockets, he seems to be stepping outside the play to make a shy adieu to the theatre he has presided over as artistic director for the past 10 years. When he slips unostentatiously out of the door, it is very moving. But it is Rylance bidding goodbye, not Prospero.